Intelligent textile composite materials containing lineal strain sensors

The distributed nature of strain sensors affects the accuracy of the measurements and the accuracy of state estimates made from the measurements. The effect of strain gage size and position on measurement errors in textile composite materials is analyzed. A statistical model for sensor output including the effects of unit cell size, strain variation within the unit cell, gage length, gage width, material defects and irregularities, and instrument error is proposed. The model is verified experimentally using a plain weave graphite-polyester composite. Recommendations are made for the use of strain gages on textile materials.; A small diameter resistive wire is incorporated into a yarn of fiberglass thereby creating a very distributed strain sensor capable of measuring strain along a line and hence the term "lineal" strain sensor. The strain sensor output relations are investigated both theoretically and experimentally. Methods of manufacturing the sensors are also discussed.; The effect of the distributed nature of lineal strain sensors on measurement accuracy is analyzed. The measurement accuracy is a function of the configuration of the sensor within the structure. Various configurations of lineal sensors are examined using statistical models. Comparisons are made to point sensors and modal sensors.; Lineal sensor yarns can be incorporated into the textile preform manufacturing process. Large arrays of sensors embedded in the structure can be constructed with relatively little effort. Methods of constructing such grids and recovering the signals are presented. The distributed measurements made by lineal sensors are compared to point measurements.